X All-optical flip-flops based on semiconductor technologies
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- Bu səhifədəki naviqasiya:
- CR>40dB CR=50dB
- CR=40dB CR>40dB CR>40dB CR=40dB CW light injected into ring 1 CW light injected into ring 2
All-optical lip-lops based on semiconductor technologies 355
Multi-Quantum Well (MQW) structures with a small-signal gain of 31dB, saturation power of 13dBm and Amplified Spontaneous Emission (ASE) noise peak at 1547nm.
1 2 Fig. 9. Experimental Setup of the all-optical flip-flop based on SOAs. -65
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-10 static switching, in case of external CW light injected into laser 2 P injected (dBm) P ou t ( dB m )
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CR=40dB CR>40dB CR>40dB CR=40dB CW light injected into ring 1 CW light injected into ring 2 -65
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laser 2 CR>40dB CR=50dB -65
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1565 laser 1
laser 2 CR>40dB CR=50dB -16
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-10 static switching, in case of external CW light injected into laser 1 P injected (dBm) P ou t ( dB m )
laser 1 laser 2
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-10 static switching, in case of external CW light injected into laser 2 P injected (dBm) P ou t ( dB m )
laser 1 laser 2
CR=40dB CR>40dB CR>40dB CR=40dB CW light injected into ring 1 CW light injected into ring 2 -16
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-10 static switching, in case of external CW light injected into laser 1 P injected (dBm) P ou t ( dB m )
laser 1 laser 2
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-8 -6 -4 -2 0 2 4 -55
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-10 static switching, in case of external CW light injected into laser 2 P injected (dBm) P ou t ( dB m )
laser 1 laser 2
CR=40dB CR>40dB CR>40dB CR=40dB CW light injected into ring 1 CW light injected into ring 2
Fig. 10. Top: optical spectra of the two states; Bottom: output power of lasers versus input power injected into cavity 1 ( left) and into cavity 2 (right).
The system can have two states. In “state 1”, light from ring 1 suppresses lasing in ring 2, reaching cavity 2 through the 50/50 coupler and saturating the SOA 2 gain. In this state, the
optical flip-flop output 1 emits CW light at wavelength λ 1 .In “state 2” light from ring 2 suppresses lasing in ring 1 (saturating SOA 1 gain), and output 2 emits CW light at wavelength λ 2 . To dynamically change state, lasing in the dominant cavity can be switched off by injecting external pulsed light with a wavelength different from λ 1 and λ 2
(λ IN =1554.5nm). In Fig. 10 experimental measurements of the two states optical spectra are investigated and a graph of the output power of both the ring lasers, versus the CW input power injected into each cavity is reported. The output contrast ratios are higher than 40dB.
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g 1 0 5 10 15 20 25 30 35 40 45 0 0.5
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Fig. 11. Experimental results of the all-optical flip-flop output.
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(b) (c)
(d) (a)
(b) (c)
(d)
Fig. 12. Measured (a)-(b) and simulated (c)-(d) behavior of the flip-flop output edges. By injecting two regular sequences of pulses into the set and reset ports, we demonstrate the dynamic flip-flop operation shown in Fig. 11. We experimentally observed that the flip-flop falling time only depends on the edge time of control pulses (5ns in this section), while the rising time is determined by the cavity length and by the length of the fiber between the two SOAs. In our setup, each ring has a cavity length of 20m corresponding to a round-trip time www.intechopen.com
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